/*
 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.graal.phases.common;

import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.java.*;
import com.oracle.graal.nodes.util.*;
import com.oracle.graal.phases.*;

public class LockEliminationPhase extends Phase {

    @Override
    protected void run(StructuredGraph graph) {
        for (MonitorExitNode node : graph.getNodes(MonitorExitNode.class)) {
            FixedNode next = node.next();
            if (next instanceof MonitorEnterNode) {
                MonitorEnterNode monitorEnterNode = (MonitorEnterNode) next;
                if (monitorEnterNode.object() == node.object()) {
                    FixedNode monitorEnterSuccessor = monitorEnterNode.next();
                    monitorEnterNode.setNext(null);
                    ((FixedWithNextNode) node.predecessor()).setNext(monitorEnterSuccessor);
                    FrameState stateAfterFirst = node.stateAfter();
                    FrameState stateAfterSecond = monitorEnterNode.stateAfter();
                    node.safeDelete();
                    monitorEnterNode.safeDelete();
                    if (stateAfterFirst.usages().isEmpty()) {
                        GraphUtil.killWithUnusedFloatingInputs(stateAfterFirst);
                    }
                    if (stateAfterSecond.usages().isEmpty()) {
                        GraphUtil.killWithUnusedFloatingInputs(stateAfterSecond);
                    }
                }
            }
        }
    }
}
